Selective plating of reeds in bulk

ABSTRACT

This concerns the bulk electroplating with gold of reed contact blades. The blades are located in insulating pots with their contact tips uppermost and extending beyond the rims of the pots. The rim and the base of the pots are metallized and, with the blades, form the cathode of the plating surface. During plating the major parts of the reeds are screened from the plating flow by the insulating sidewalls of the pots, gold being plated only on the exposed contact tips.

United States Patent SELECTIVE PLATING OF REEDS IN BULK 10 Claims, 5 Drawing Figs.

US. Cl 204/15, 204/27, 204/212, 204/222, 204/224, 204/297 R Int. Cl C23b 5/48, C23b 5/58,C23b 5/68 Field of Search 204/15, 297 R, 27, 212, 213, 222, 224, 297 R [56] References Cited UNITED STATES PATENTS 2,505,531 4/1950 Ellwood 204/222 2,721,837 10/1955 Backer..... 204/201 3,184,655 5/1965 Brown 204/297 3,275,542 9/1966 Couture 204/222 3,276,986 10/1966 Swistun 204/15 3,397,126 8/1968 Gilbert 204/222 3,462,350 8/1969 Gannoe 204/202 Primary Examiner-John H. Mack Assistant ExaminerT. Tufariello Attorneys-C. Cornell Remsen, .lr., Walter J. Baum, Percy P. Lantzy, J, Warren Whitesel, Delbert P. Warner and James B. Raden ABSTRACT: This concerns the bulk electroplating with gold of reed contact blades. The blades are located in insulating pots with their contact tips uppermost and extending beyond the rims of the pots. The rim and the base of the pots are metallized and, with the blades, form the cathode of the plating surface During plating the major parts of the reeds are screened from the plating flow by the insulating sidewalls of the pots, gold being plated only on the exposed contact tips.

SELECTIVE PLATING F REEDS IN BULK This invention relates to a method of selectively electroplating a batch of elongated members each over a region adjacent one end, and can be used for goldplating the contact tips of reeds for use in reed contact units.

FIG. I shows a typical reed of this type. It consists of a blade I and a shank 2, and the requirement is to goldplate the blade over a region adjacent its end 3, i.e. the region at which it will make contact with the cooperating reed, while keeping the shank substantially free of plating so that a good seal can be made when the reed is finally sealed into its envelope.

A conventional method of achieving this requires that each reed be loaded one by one manually into ajig, and then the jig inverted and lowered into a plating bath so that only the blades enter the bath. Clearly this loading operation is very time consuming, and a further disadvantage of this method is that the electrolyte leaves a tide mark around the reed where the latter enters the surface of the electrolyte.

According to the present invention there is provided a method of selectively electroplating a batch of elongated members each over a region adjacent one end, wherein the members are plated while completely immersed in electrolyte and located in a container having an opening out of which the said ends project, the major parts of the members being screened from the plating flow by insulating walls of the container.

More specifically, the invention provides a method of selectively electroplating a batch of elongated members each over a region adjacent one end, wherein the members are located in a container having walls of insulating material with the said one ends projecting out of an opening of the container, the container having at least one cathode making electrical contact with the batch of members, and while the members are completely immersed in electrolyte a potential difference is applied between the cathode and an anode arranged outside the container, the arrangement being such that the plating flow is screened from the major part of each member by the insulating walls but not from its said one end, and the members are agitated to expose them substantially uniformly to the plating flow.

An embodiment of the invention suitable for the plating of reeds will now be described, by way of example, with reference to FIGS. 2 to of the accompanying drawings, in which:

FIG. 2 is a cross-sectional view of apparatus suitable for electroplating the contact tips of a batch of reeds of the type shown in FIG. 1;

FIG. 3 is a view on the line 33 of FIG. 2 and looking in the direction of the arrows;

FIG. 4 shows the orientation of the reeds in the insulating vessels of the apparatus of FIGS. 2 and 3, and

FIG. 5 shows a reed plated by the method described.

Referring to the drawing, the apparatus comprises a number of containers or pots 4, in this case six, carried by a support member or rack 5. Each pot 4 comprises side walls 6 and a base 7, and sandwiched between these, against an annular step 9 in the sidewalls is a disclike cathode 8. A further cathode 10, in the form of a circular wire loop, is carried near the top of the sidewalls 9 on the inside of the pot.

The sidewalls and base of the pot are made of insulating material; we have found perspex to be suitable but other insulating materials can be used. The loop 10 and the disc 8 can be of copper, the latter being goldplated to prevent contamination of the electrolyte in the pot.

The rack 5 carrying the pots 4 is itself carried by a tubular member 11. The rack 5 and tubular member 11 are also of insulating material, and we have found PVC to be suitable for this purpose.

One end of each wire loop extends through the respective sidewalls 6 and through the wall of the tubular member II and is there soldered to a respective lead 12. The leads 12 extend to the top of the tubular member 11 to the cathode terminal 13.

Each disc 8 is connected to its respective loop 10 by an insulated lead 14 soldered at one end to the underside of the disc and at the other to the extension of the loop and passing through respective bores in the base 7 and rack 5. The soldered connections of the lead 14 to the disc and loop are preferably given a coating of protective material, such as Araldite (R.T.M.).

To plate the reeds, respective batches of reeds are loaded into the pots 4 with their blades uppermost. We have found that the optimum number of reeds in each batch should be such as to approximately one-third fill the cross section of the pot if stood vertically in the pot. The lower part of the apparatus is then lowered by the member 11 into the gold-electroplating solution (electrolyte) I5 so that the reeds and pots are completely immersed and surrounded as shown by a cylindrical anode 16.

An appropriate potential difference is applied between the cathode terminal 13 and the anode I6 and the pots are subjected to a high-speed horizontal orbital movement. This is achieved in known manner by applying a transverse orbital movement to the tubular member 1!.

When vibrated in this way the reeds in each batch take up orientations as shown in FIG, 4. The pots are dimensioned so that the ends 3 of the blades project out of their open tops, approximately two-thirds of the blade length projecting above the rim. The orbital vibration of the pots agitates the reeds and causes a general migration of the reeds around the pots in the same direction as the orbital vibration (the direction of the arrow in FIG. 4). The agitation ensures that gas bubbles forming on the reeds are removed, i.e. the reeds are depolarized, and exposes them substantially uniformly to the plating flow so helping in obtaining a consistent plating on all the reeds.

Typically, we load 250 reeds into each pot, thus 1,500 reeds can be processed at a time. The diameter of the orbital motion we have found suitable is about 20 thousandths of an inch and the frequency about 1,000 r.p.m. The potential difference applied across the anode and cathode, and the plating time, will naturally depend upon the particular circumstances such as the plating thickness required.

The position of the anode I6 is chosen so that the shanks of the reeds and the lower part of the blades are screened from the plating flow, which is directional, by the insulating sidewalls of the pots.

A plated reed is shown in FIG. 5, the strength of shading indicating the thickness of the deposited gold layer. It can be seen that due to the screening of the pots the plated deposit is thickest at the contact tip and falls away rapidly down the blade. At the lower end of the shanks, however, there may be a slight deposit due to the drainage holes 17 in the bottom of the pots 4. This is no disadvantage since the major central part of the shanks, at which the reed is subsequently sealed into its envelope, is kept relatively free of gold by the screening effect of the sidewalls 6.

The method of the invention is not limited to the plating of reeds, nor to goldplating. Although the apparatus described above has been found most satisfactory for our purpose, other arrangements are possible. For example, either a disclike cathode 8 at the base or a circular cathode I0 at or near the top rim of the pot can be used on its own, although better contact is made to the batch, of reeds if both are used. These cathodes can be formed in an alternative manner to that described by metallizing the base and the rim of the pots, and it is contemplated that other anode and cathode arrangements are possible. It is also contemplated that in some circumstances a vibration of the pots other than an orbital movement would prove satisfactory, such as a random transverse vibration. In addition an embodiment is possible in which the pots lie on their sides with an opening facing horizontally. In this case the reeds would lie horizontally along the bottom wall of the pots, and could be suitably agitated by rotating the pots. Means would then be required to prevent the reeds from working their way out of the pots. This problem would not arise, however, if the pots were set at an acute angle to the horizontal.

The method described of plating the contact tips of reed blades has the following advantages:

a. Blades are plated in bulk (no individual mounting into plating jigs or racks).

b. During the plating cycle the blades are completely immersed in the solution (thus avoiding the contamination and gassing which always occurs on the surface of the bath), but are plated only in the contact area, thus minimizing the gold cost.

c. Low cost operation. Typically 1,500 blades are plated, in bulk, in a tank inches diameter X 5 inches deep with cycle time of 2- minutes. This quantity can be greatly increased without a relative increase in the tank size.

d. Elimination of tide mark mentioned previously.

e. Minimum labor involvement.

t. All associated processes (preclearing, etc.) can be carried out in the same racked pots.

it is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not to be considered as a limitation on its scope.

We claim:

1. A method for selectively electroplating a batch of elongated members each over a region adjacent one end, comprising the steps of placing elongated members to be plated in a container, orienting the elongated members in the container so that portions to be plated protrude through an opening in the container while portions not to be plated are screened by the walls of the container, immersing the container with the elongated members in an electrolyte, and plating the protruding portions of the elongated members.

2. A method for selectively electroplating a batch of elongated members each over a region adjacent one end, wherein the members are positioned in a container having walls of insulating material with the said one ends projecting out of an opening of the container, the container having at least one cathode making electrical contact with the batch of members, immersing the container in an electrolyte to completely cover the elongated members, applying a potential difference between the cathode and an anode arranged outside the container, the arrangement being such that the plating flow is screened from the major part of each member by the insulating walls but not from the said one ends, and agitating the members to expose them to substantially uniform plating flow.

3. The method claimed in claim 2, wherein the container is open-topped and the said one ends project out of the open top.

4. The method claimed in claim 3 wherein the elongated members are reeds which are located in the container with their contact blades uppermost.

5. The method claimed in claim 4 wherein the blades are to be plated with gold.

6. The method claimed in claim 3 wherein the container is of circular cross section.

7. A method for selectively electroplating a batch of reeds with gold each over a region adjacent the end of its contact blade, wherein the reeds are located in a circular container having an opening at the top and sidewalls of insulating material with the contact blades projecting out of the opening, the container having at least one cathode making electrical contact with the batch of reeds, and while the reeds are completely immersed in a goldplating electrolyte applying a potential difference between the cathode and an anode ar ranged to the side of the container, the arrangement being such that the plating flow is screened from the major part of each reed by the insulating sidewalls but not from the end of its blade, and the container is vibrated to agitate the reeds to expose them substantially uniformly to the plating flow.

8. The method claimed in claim 7 wherein the container is vibrated with a high-speed horizontal orbital movement to agitate the members or reeds.

9. The method claimed in claim 7, wherein a cathode is located at the base of the container.

10. The method claimed in claim 7, wherein a cathode is located around the inside of the container at or near its open- 

2. A method for selectively electroplating a batch of elongated members each over a region adjacent one end, wherein the members are positioned in a container having walls of insulating material with the said one ends projecting out of an opening of the container, the container having at least one cathode making electrical contact with the batch of members, immersing the container in an electrolyte to completely cover the elongated members, applying a potential difference between the cathode and an anode arranged outside the container, the arrangement being such that the plating flow is screened from the major part of each member by the insulating walls but not from the said one ends, and agitating the members to expose them to sUbstantially uniform plating flow.
 3. The method claimed in claim 2, wherein the container is open-topped and the said one ends project out of the open top.
 4. The method claimed in claim 3 wherein the elongated members are reeds which are located in the container with their contact blades uppermost.
 5. The method claimed in claim 4 wherein the blades are to be plated with gold.
 6. The method claimed in claim 3 wherein the container is of circular cross section.
 7. A method for selectively electroplating a batch of reeds with gold each over a region adjacent the end of its contact blade, wherein the reeds are located in a circular container having an opening at the top and sidewalls of insulating material with the contact blades projecting out of the opening, the container having at least one cathode making electrical contact with the batch of reeds, and while the reeds are completely immersed in a goldplating electrolyte applying a potential difference between the cathode and an anode arranged to the side of the container, the arrangement being such that the plating flow is screened from the major part of each reed by the insulating sidewalls but not from the end of its blade, and the container is vibrated to agitate the reeds to expose them substantially uniformly to the plating flow.
 8. The method claimed in claim 7 wherein the container is vibrated with a high-speed horizontal orbital movement to agitate the members or reeds.
 9. The method claimed in claim 7, wherein a cathode is located at the base of the container.
 10. The method claimed in claim 7, wherein a cathode is located around the inside of the container at or near its opening. 